The need for a reliable and valid clinical instrument for making psychiatric diagnoses according to the official classification of mental disorders, DSM-III, is widely acknowledged. This is a project to determine the test-retest reliability of such an instrument, the Structured Clinical Interview for DSM-III (SCID), that is being developed under contract with NIMH. This project, focusing on determining the reliabiity of the SCID, will provide the basis for later work on studying the validity of the SCID and the DSM-III categories themselves. So that the SCID can be tested in a variety of health care settings and with community subjects, the work will be done in six collaborating sites: New York State Psychiatric Institute (Columbia), Long Island Jewish-Hillside Medical Center (SUNY), Substance Abuse Treatment Unit (Yale), McLean Hospital (Harvard), Harvard Community Health Plan (Harvard), and the Los Angeles Epidemiologic Catchment Area research project (UCLA). The project will begin with the revision of the instrument at the NYSPI site, followed by a six month period of field testing and debugging in all six sites. Psychiatric subjects will be selected to ensure that all of the diagnoses covered by the SCID are represented. Primary care facility subjects will be selected based on General Health Questionnaire scores. The community subjects will be selected based on prior DIS data. The test-retest reliability will be determined on 500 subjects from the six sites, stratified to ensure that, as far as possible, for all of the specific SCID diagnoses there are at least 20 subjects. This nine month period will include both intra and inter-center test-retest reliability studies.